[GHC] #13022: Pattern Synonyms using other synonyms causes ghc panic

[GHC]

#13022: Pattern Synonyms using other synonyms causes ghc panic
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           Reporter:  AveryGlitch    |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Linux
       Architecture:  x86_64         |   Type of failure:  Compile-time
  (amd64)                            |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 Here's a (somewhat) minimal example:

 {{{#!hs
 {-# LANGUAGE PatternSynonyms #-}

 data Some = Thing Int Int


 pattern A x = Thing x 0
 pattern B x = Thing x 1
 pattern C x = Thing x 2

 pattern D = C 3
 }}}

 And here's what happened when I tried to load this into ghci:
 {{{
 *Main> :l ghc_bug.hs
 [1 of 1] Compiling Main             ( ghc_bug.hs, interpreted )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.1 for x86_64-unknown-linux):
         kindPrimRep.go rep_a3fP

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13022>
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